In the diagnosis and treatment of breast cancer, it is often necessary to perform a biopsy to remove tissue samples from a suspicious mass. The suspicious mass is typically discovered during a preliminary examination involving visual examination, palpation. X-ray, magnetic resonance imaging (MRI), ultrasound imaging or other detection means.
When a suspicious mass is detected, a sample may be taken by biopsy, and then tested to determine whether the mass is malignant or benign. This biopsy procedure can be performed by an open surgical technique, or through the use of a specialized biopsy instrument such as stereotactic needle biopsy. To minimize surgical intrusion, a small specialized instrument such as a biopsy needle may be inserted in the breast while the position of the needle is monitored using fluoroscopy, ultrasonic imaging, X-rays, MRI or other suitable imaging techniques.
Regardless of the method or instrument used to perform the biopsy, subsequent examination of the surgical site may be necessary, either in a follow up examination or for treatment of a cancerous lesion. Treatment often includes a mastectomy, lumpectomy, radiation therapy, or chemotherapy procedure that requires the surgeon or radiologist to direct surgical or radiation treatment to the precise location of the lesion. Because this treatment might extend over days or weeks after the biopsy procedure, and the original features of the tissue may have been removed or altered by the biopsy, it may be desirable to insert a site marker into the surgical cavity to serve as a landmark for future identification of the location of the lesion.
Commonly assigned U.S. application Ser. No. 11/242,334 discloses markers that use expandable filament portions to ‘hold’ a site marker in place within a biopsy cavity. That is, a site marker may include a bio-absorbable expandable portion, such as a suture, with a marker attached thereto, where the marker is visible under multiple modalities and the suture will inhibit migration of the marker within the biopsy cavity. The expandable portions of these structures typically define a site marker diameter that is greater than the outer diameter of a deployment cannula of a site marker deployment device. To insert a site marker within a biopsy site, the site marker is compressed (at least partially elastically deformed) to a dimension that will permit the site marker to be at least partially interposed within the cannula, the site marker and cannula are sterilized, the cannula is inserted within the biopsy canal such that the opening of the cannula is within the biopsy site, and the marker is deployed into the biopsy site. Once deployed, the site marker will expand as the marker exits the cannula in reaction to the elastic deformation. The site marker will expand until the elastic deformation is eliminated or portions of the site marker interfere with the inside portions of the biopsy cavity.
Precise placement of site markers is important for subsequent evaluation of the biopsy area. Current methods of marker deployment generally include locating the outer cannula of the biopsy instrument in the area of the lesion, then depressing a plunder or pushrod within the cannula to force the marker into a biopsy cavity. When the plunger or pushrod is depressed, however, the site marker may not be placed exactly where intended. For instance, if the cannula is placed at the center of a biopsy cavity, the marker may move from the center of the cavity to one side, making the marker more difficult to subsequently locate. Furthermore, varying amounts of pressure on the pushrod may cause the site marker to extend further into the cavity than desired.
Accordingly, there is a need for a site marker deployment device and/or method which allows more precise placement of a site marker within a biopsy cavity.